Wednesday, May 21, 2008

Don’t Be Afraid of Fats: Part I

When I was growing up I learned that fats were “bad.” I remember eating “fat-free” foods in abundance as a teenager and young adult. The misinformation that created media hype about fats being harmful continues today and I’d like to offer an alternative discussion. My intention is to offer an introduction to fats that will include:
• What are fats
• What’s the difference between them
• Good fats vs bad fats
• What should I be eating.

In order to begin this discussion, it’s important to know that there are many different types of fat and what makes each different is their chemical make-up. All fats are comprised of carbon atoms and hydrogen atoms. If a carbon atom doesn’t have a hydrogen atom attached to it, it has a double bond instead. Depending on how many of each results in the different types of fat. Even though I’m not fond of chemistry myself, it helps to understand a bit of it when talking about fats.

Saturated fat: This fat’s chemical structure results in it being solid at room temperature. Saturated fat has no double bonds. These fats are stable and will not go rancid, which means they are good for using at high heats such as sautéing or baking. These fats include man-made creations such as margarine but also animal fat such as butter, lard, or meat, or tropical oils such as coconut or palm oil. It’s important to keep in mind that there are different types of saturated fats and they are not created equal. More on this in Part II.

Monounsaturated fat: This fat differs from saturated fat in that it has fewer hydrogen atoms which means that it is most commonly liquid at room temperature. These fats generally are stable and like saturated fat can be used with heat. Common sources of monounsaturated include fat from almonds, pecans, cashews, peanuts and avocados.

Polyunsaturated fat: This type of fat has even fewer hydrogen atoms than monounsaturated so it will always be liquid and often needs to be refrigerated to keep it from going rancid. You may be familiar with this category of fats which include the terms “omega-6” or “omega-3” essential fatty acids. Omega-6 and omega-3 fats differ in the number of double bonds; omega-6 have 2 double bonds and omega-3 have 3 double bonds. Because of this chemical structure, these oils are very reactive, meaning their chemical composition can change (in a negative way) and therefore cannot be used in cooking or baking. The sources of these oils are vegetables and plants such as corn, safflower, canola, soybean, flax seed, hemp seed but also marine sources such as cold-water fish and algae. The body cannot make polyunsaturated fat so it must be included in the diet.

Even though I listed 3 separate categories of fats, in reality fats are a combination of the 3 types. For example lard is 40% saturated, 48% monounsaturated, and 12% polyunsaturated; olive oil is 75% monounsaturated, 13% saturated, 10% omega-6 and 2% omega-3. So, although olive oil is a predominantly a monounsaturated fat, because it also has omega-6 and omega-3 fats present, it’s generally not recommended for heated food preparation.

That’s my general introduction to fats. In the next installment, I’ll start talking about good vs bad fats.

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